Re: CM1200 speed issue with Xfinity Gigabit service

Vojt · ‎2019-08-13

Hello,

I have gigabit service with Xfinity, and I did a speed test and pulled 950mbs, instead of renting the XB6 I purchased the CM1200, now my speeds are ~450MBps. I did not configurations on the CM1200

I have a funky setup, I have the 4 ethernet ports on the CM1200 taken up, one goes into another switch which then goes into my other devices. Another ethernet port is for another switch that has more devices. Would it be better to daisy chain and just use 1 ethernet port from the CM1200 into the switch as opposed to using them all on the modem?

Thank you in advance!

FURRYe38 · ‎2019-08-13

No, for the CM1200, only LAN port 1 is to be used with a single NAT router behind it.

Lan ports 1 and 2 support Link aggregation which you need a LAG supporting router to beable to take advantage of this feature. R7960P or R8000P which support LAG.

The other ports 3 and 4 are for ISP static IP assigned addresses mostly seen in business class environtments.

So for basic home needs, if you don't have a LAG supporting router, disable LAG on the CM modem and connect your main host router to port #1 only and leave the others disconnected on the CM modem.

Vojt · ‎2019-08-13

Hi,
Thank you for your response! I have a switch attached to port 1 of the CM1200, and another switch is attached to that switch, but all other ports on the modem are empty and all lights are green.

I have tried a direct connection to the computer and modem, didn't help. I am not running wireless, only wired.

FURRYe38 · ‎2019-08-14

You need to move the switches OFF the modem and connected them behind a router.

I would reset the modem and setup from scratch with a NAT router connected at Port #1. Have a wired PC connected to the NAT router. Might need to reset the NAT router and setup from scratch.

I have this same modem, tested it for NG. Works well with my R7960P router, both in single port #1 and LAG modes.

Vojt · ‎2019-08-14

Thank you for the feedback! What if I do not need a wireless router, any other recommended routers?

FURRYe38 · ‎2019-08-14

For any CM modem, since these do not have any router or wifi functions, you need some form of a NAT router. Modem>Router>Switch<Lan connected devices to switches or directly to Router. This is standard networking connection configurations.

Most any router will work. NG Orbi, R or XR series routers. You can see my tag signature for routers I have that work with the CM modems I have.

Most router now days come with wifi built in. If you don't need wifi, then you could try Ubiquity's Edge Router X as it's a wired only router. I have this router as well. No wifi. I believe they have a few models with out WiFi. NG and other router Mfr have the built in wifi routers now days.

Sleepdoc502 · ‎2020-01-24

Thanks for your help. I see that ethernet port aggregation is disabled for the CM1200 and I have disaconnected the other LAN devices I had connected. I reset the ORBI and was able to connect it to the internet. I now have problems with the sattelites connecting to the ORBI. While I upgraded the the cable modem, my whole house connectivity is markedly worse.

FURRYe38 · ‎2020-01-25

Please post over in the Orbi forum and we'll help you out.

https://community.netgear.com/t5/Orbi/bd-p/Orbi

30 feet is recommended in between RBR and RBS to begin with depending upon building materials when wirelessly connected. https://kb.netgear.com/000036466/How-far-should-I-place-my-Orbi-satellite-from-my-Orbi-router

Good Luck.

@Sleepdoc502 wrote:

Thanks for your help. I see that ethernet port aggregation is disabled for the CM1200 and I have disaconnected the other LAN devices I had connected. I reset the ORBI and was able to connect it to the internet. I now have problems with the sattelites connecting to the ORBI. While I upgraded the the cable modem, my whole house connectivity is markedly worse.

kioteh · ‎2020-03-23

I'm having a very similar situation. Here's my setup.

cm1200 Nighthawk cable modem

RAX200 Nighthawk router

When I connect my Xfinity cable modem I see speeds of 950Mbps speeds. But when I swap it out for the cm1200 I see my speeds drop to 500Mbps. Any thoughts on why this might be? I really really like the features of the RAX200 so was hoping to use it but with the drop in speeds I'm seeing I'm going to have to stick with the Xfinity modem unless I can figure out why.

FURRYe38 · ‎2020-03-23

Have the ISP check the signal and line quality UP to the modem.
Be sure there are not coax cable line splitters in the between the modem and ISP service box.
Be sure your using good quality RG6 coax cable up to the modem.

Be sure the ISP has provisioned the CM modem correctly.

Wire speed test with a PC directly connected to the CM1200 modem with out any router in the mix.
Be sure to reset the CM and RAX devices and set up from scrach. Speed test again with the RAX in the mix with a wired PC.

@kioteh wrote:
I'm having a very similar situation. Here's my setup.

cm1200 Nighthawk cable modem
RAX200 Nighthawk router

When I connect my Xfinity cable modem I see speeds of 950Mbps speeds. But when I swap it out for the cm1200 I see my speeds drop to 500Mbps. Any thoughts on why this might be? I really really like the features of the RAX200 so was hoping to use it but with the drop in speeds I'm seeing I'm going to have to stick with the Xfinity modem unless I can figure out why.

kioteh · ‎2020-03-23

"Have the ISP check the signal and line quality UP to the modem. "

-Had the ISP out on Friday and checked all connections up to the modem. As mentioned in my original post, the speed is fine if I change back to the ISP's modem, but see instant drop when I put the Netgear modem in.

"Be sure there are not coax cable line splitters in the between the modem and ISP service box."

-There are not.

"Be sure your using good quality RG6 coax cable up to the modem."

-ISP replaced the tips just to be sure, but again if it works fine with ISP modem I don't think this would be the case

"Be sure the ISP has provisioned the CM modem correctly."

-Not sure what all I can check here. Once I plug in the cm1200 Xfinity sends me a message to provision it and then it starts working, just not as fast. Any settings on the modem itself I should be checking?

"Wire speed test with a PC directly connected to the CM1200 modem with out any router in the mix. "

-When I'm performing my speed checks its just with the laptop plugged directly in to the cm1200.

"Be sure to reset the CM and RAX devices and set up from scrach. Speed test again with the RAX in the mix with a wired PC."

-I can do this again if need be but I set the entire thing up with the assistance of Netgear phone support. Is there something that you would expect this to change in particular?

Are other people able to get 900+ Mbps using the cm1200? Is there any setting in particular that I might want to check for?

FURRYe38 · ‎2020-03-23

Just be cause the one modem on the line works and the other doesn't, doesn't mean that the signal on the coax line is good for the CM1200. Something to be sure you have the ISP check while the CM modem is online. They can see whats going on...

LAG (Link Aggregation) should be disabled, just check for this on the CM modem.

So when your Laptop is directly connected to the CM modem, it's not seeing anything near 900Mbps? Correct?

Try swapping to the 2nd port on the back.

I think others do, i know this as one issue with the CM1200 that users have reported is that after enabled LAG on the 1200, there speeds drop. Disabling it keeps the speed up and near 900Mbps. I have this modem however I'm using a CM1100 at the moment as I'm doing other fun stuff.

Wolfen620 · ‎2020-03-23

I am currently using the cm1200 with factory settings and I am getting 930 down and 50 up with xfinity service.

kioteh · ‎2020-03-23

Excellent. That makes me feel much better. I'll try disabling Aggregated ports tonight and see if that helps.

FURRYe38 · ‎2020-03-23

Let us know how it goes...

kioteh · ‎2020-03-23

Weird. Still no dice. I did a speedtest on boot up with my Xfinity supplied cable modem:

Ping - 14ms

Download - 926.24

Upload - 40.01

Then I hooked up my Netgear cm1200 and factory reset it to insure all settings were default and performed another speed test.

Ping - 15ms

Download - 606.29

Upload - 29.45

Do I just have a faulty one?

FURRYe38 · ‎2020-03-24

Yes. You might try another CM modem...

kioteh · ‎2020-03-24

Thanks for all the advice guys, greatly appreciate the responses. Here's where I stand as of this morning.

- I contacted Netgear support last night and worked with a tech on the call to check all of my cm1200 settings (after a reset to factory). The tech noticed that the power levels for the upload and download channels looked off and stated that Xfinity needed to reprovision the device and that I would need to contact them directly.

- I contacted Xfinity this morning and they reprovisioned the device but I was still seeing only 600 Mbps download. After troubleshooting with the Xfinity tech more he stated that an Xfinity tech would need to come to my house to complete my upgrade to a 1 Gbps plan and scheduled a time for this upcoming Friday. To me, this makes no sense seeing as I can swap out my Netgear modem with my old Xfinity modem and get 950 Mbps. No matter how much I explained this though he was saying I still have to have a tech out. So now I wait for Friday. I'll update back here after that visit to get closer for anyone who might track this thread in the future.

FURRYe38 · ‎2020-03-24

Well what may work for other modems may not work for others. Let the tech come out and check it all. Have the CM1200 online with a wired PC connected directly to the CM modem. Have only Ooklas installable speed test app on your PC running. Disable or exit from all other applications while hes there and heling you test. Take notes and if even after the tech has made any adjustments and can't get the CM modem to speed out at near 900Mbps, then get this information to your NG support case and see about getting an RMA.

@kioteh wrote:
Thanks for all the advice guys, greatly appreciate the responses. Here's where I stand as of this morning.

- I contacted Netgear support last night and worked with a tech on the call to check all of my cm1200 settings (after a reset to factory). The tech noticed that the power levels for the upload and download channels looked off and stated that Xfinity needed to reprovision the device and that I would need to contact them directly.

- I contacted Xfinity this morning and they reprovisioned the device but I was still seeing only 600 Mbps download. After troubleshooting with the Xfinity tech more he stated that an Xfinity tech would need to come to my house to complete my upgrade to a 1 Gbps plan and scheduled a time for this upcoming Friday. To me, this makes no sense seeing as I can swap out my Netgear modem with my old Xfinity modem and get 950 Mbps. No matter how much I explained this though he was saying I still have to have a tech out. So now I wait for Friday. I'll update back here after that visit to get closer for anyone who might track this thread in the future.

CharmedKub · ‎2020-06-04

Can you share with me all your CM1200 settings, so I can match mine?

FURRYe38 · ‎2020-06-04

Only setting that you can configure is LAG and that should be disabled.

lazybone · ‎2020-08-02

I was reading through this thread and my issue is different. I’m currently experiencing slow wifi speeds, I use to rent xfinity modem and I was averaging 400-450Mbps solid, switched over to cm1200 June 29,2020 averaged 400-450mbps after the first month I noticed my speeds at most 200-250Mbps and now it has dropped to 100-150mbps and under 20mbps at times. I’ve spoken to several Xfinity reps they say my signal is good and they also have reset the signal sent to my cm1200. I have not changed anything since I have set up my cm1200. My set up is cm1200+r8000 router.

FURRYe38 · ‎2020-08-03

Be sure to test with wired connections thru the router and modem.

Wifi speeds results may not be accurate due to many factors that contribute to innaccurate results.

Be sure there are no coax cable line splitters in the between the modem and ISP service box.
Be sure your using good quality RG6 coax cable up to the modem.

@lazybone wrote:
I was reading through this thread and my issue is different. I’m currently experiencing slow wifi speeds, I use to rent xfinity modem and I was averaging 400-450Mbps solid, switched over to cm1200 June 29,2020 averaged 400-450mbps after the first month I noticed my speeds at most 200-250Mbps and now it has dropped to 100-150mbps and under 20mbps at times. I’ve spoken to several Xfinity reps they say my signal is good and they also have reset the signal sent to my cm1200. I have not changed anything since I have set up my cm1200. My set up is cm1200+r8000 router.

persiancowboy · ‎2020-08-27

I've had the same problem and after many hours of Xfinity tech support, they reached the conclusion that the Netgear modem is not capable of delivering the gigabyte speed that they claim on the package.

persiancowboy · ‎2020-08-27

They did the same with me and replaced the line to the house, no difference. It's the modem or something in the modem settings that does not allow it to get the higher speed that Netgear advertises. Unfortunately my free support period is expired and the Netgear wanted me to pay about $150 to troubleshoot this for me. So I decided to just pay that money and buy a new Xfinity modem directly from them.